For the D&D 3.5e sheet, there is no place to put Dodge bonuses. All Dodge bonuses should stack, and they should affect TouchAC but not FFAC. There is no field in the AC row that currently operates like that.
I've put my Dodge bonus into the Dex field by overwriting it manually, but that's clearly not sustainable (for when the Dex ability changes). Those boxes are wide enough to hold multiple digits, so I'm hoping another box can be added just for Dodge bonuses.
In a perfect world, it would allow a formula to be entered. This would allow for the future addition of a Conditions area where conditions could be turned on/off with a checkbox and appropriate fields on the sheet would be updated. Turning on Total Defense or Fighting Defensively, for example, would add to the Dodge field, but when turned off would revert. Adding the bonus in directly and getting a new number is fine, but seeing "+1+2+1" because of Dodge + Fighting Defensively + TumbleBonus might make it easier to remember where those values are coming from. Again, in a perfect world, a tooltip over the field would provide a full breakdown.